1. Field of the Invention
The present invention relates to ball type trailer hitches. In particular, the invention relates to securing trailer hitch balls on towing vehicles to prevent them from becoming loose or disengaged.
2. Description of the Related Art
Ball type trailer hitches are commonly used for towing various types of vehicles and trailers (hereinafter referred to as trailers). Ball type hitches are usually a simple hitch ball mounted onto the rear of a towing vehicle. Mounting is either directly on the medial step portion of the bumper in the case of trucks or on a drawbar for a variety of towing vehicles. A drawbar can either be directly mounted to the vehicle or fit into a receiver mounted to the towing vehicle that is designed to receive the drawbar. A mating socket type device used to engage the hitch ball is then mounted onto the front of the trailer being towed. Most hitch balls are mounted by a means of a threaded mounting shaft and cooperating locking nut or lock washer and nut combination. Specifically, the threaded mounting shaft extends through a hole in the bumper or drawbar and the locking nut or nut and locking washer are snugly tightened against the bumper/draw bar to secure the trailer hitch ball in position.
A problem often occurs when these nuts are tightened. The hitch ball rotates relative to the bumper/draw bar then it is not possible to complete the tightening operation unless tools are employed to prevent this rotation.
One way of addressing this problem is disclosed in U.S. Pat. No. 5,040,817 to Dunn. The pedestal or upper portion of the hitch ball mounting shank in Dunn includes wrench flats that allow the ball to be held in position with a wrench during the nut tightening operation. This procedure stops rotation but still involves the use of two tools, one wrench to secure the hitch ball mounting shaft from rotation and one wrench to tighten the securing nut. Manipulation of two tools is inconvenient, difficult or even impossible for some handicapped people. Moreover, two tools are not always available to allow the connection to be made. The use of tools can scratch the finish of the hitch ball. This finish is frequently chrome for a cosmetic reason and when scratched or marred can expose the ball surface to the elements and eventual unsightly rusting.
The use of two tools was avoided and disclosed in U.S. Pat. No. 5,884,931 to McCoy. However, McCoy requires the use of a locking element along the shank for cutting a mating periphery in the receiving hole (passageway) of the bumper/draw bar. This approach requires meeting tight tolerances between mating parts and appropriate metal hardness between the parts to be effective. The McCoy design has limitations for retrofit to solve the problem of ball rotation on equipment already in the field because of these locking element tolerances. The manufacturing process to produce such a locking element along the shaft can be complicated and could limit the use of some standard parts.
It is also known in the art that hitch balls become loose after the initial installation. They can turn, eventually tilt, and then can come off tow vehicles if not tightened or welded in place. This can occur when a trailer is attached and in tow and result in an accidental trailer disconnection from the tow vehicle. Such accidental disconnects can cause damage to the trailer and cargo. Even worse, vehicles sharing the highway on which the trailer is being towed can be hit and damaged by the accidentally disconnected trailer, and the occupants of the other vehicles struck by the accidentally disconnected trailer may suffer serious or fatal injuries. Accidental disconnects can be reduced by the inventions covered in Milazzo U.S. Pat. Nos. 5,947,504 and 6,155,587 and the current invention can be used in conjunction with developments in these patents.
Accordingly, recognizing these and other shortcomings in the related art a need still exits for an improved, less complicated, more readily producible assembly which prevents rotation and tilting of the hitch ball and shaft relative the bumper/draw bar.